Radar Detection Signal Interference Law And Gain Method Of Defects Behind Highway Tunnel Reinforced Concrete Lining

Ground penetrating radar has become the main method for detecting the integrity of the shallow layer of highway tunnel lining structure due to its advantages of flexible use,strong adaptability,intuitive data,and high detection accuracy.However,due to the absorption of electromagnetic waves by the reinforcement of the tunnel lining,it is difficult for the ground penetrating radar to detect defects and diseases behind the lining,which severely restricts the development of the exploration technology of the tunnel’s internal operating state.Therefore,this paper first carried out numerical simulation to study the mechanism of the transmission of the steel bar on the ground penetrating radar wave;on this basis,the road tunnel lining ground penetrating radar scanning physical model test was carried out to study the lining steel bar to identify the defect behind the lining radar.The influence mechanism of the signal;through the statistical analysis of the ground penetrating radar signal of the defect behind the reinforced concrete lining,the method of gaining the GPR signal of the defect behind the reinforced concrete lining of the highway tunnel is proposed.The main work and results of this paper are as follows:(1)The forward modeling of the disease behind the reinforced concrete lining based on the finite difference time domain method was carried out,and the method of detecting the buried depth of the disease by the hyperbolic principle of the point target under the condition of the steel layer was improved,and it was revealed that the radar detects different filling media under the action of the steel layer.The imaging law of cavity disease and the law of electromagnetic wave transmission.(2)Carried out ground penetrating radar scanning defect behind reinforced concrete lining model test,revealing the influence law of ground penetrating radar in detecting defects behind reinforced concrete lining,size interpretation radar signal error,and proposing the radar waveform of defect behind tunnel lining Gain index.(3)The signal gain method of ground penetrating radar under the influence of the reinforced layer was studied,the radar amplitude characteristics of the defects behind different reinforced concrete linings were extracted,and the amplitude gain formula suitable for the interpretation of the radar signals of the defects behind the tunnel lining was proposed.